Centralized lubrication system

ABSTRACT

A centralized lubrication system of the type in which a distributor periodically injects a predetermined quantity of lubricant to each of a plurality of lubrication sites in a predetermined sequence, including sensor means associated with each of the sites, a control means which receives signals from each of the sensor means, and an auxiliary delivery means actuated by the control means to inject additional amounts of lubricant to flood the lubrication site when the sensor associated with that site indicates that an excessive temperature has been reached. The control means may also include means for resetting the sensors after the condition of excessive temperature is reached to determine whether the flooding of the site has been effective to reduce the temperature below the predetermined maximum. Additionally, the system may include a timer which cuts off the additional supply of lubricant and signals that the particular site is in such a condition that additional amounts of lubricant are ineffective to reduce the temperature to an acceptable value.

United States. Patent Roberts [45] July4, 1972 [54] CENTRALIZED LUBRICATION SYSTEM [72] Inventor: Robert D. Roberts, Streetsboro, Ohio [73] Assignee: Houdaille Industries, luc., Buffalo, N.Y.

[22] Filed'. June 30, 1970 [2l] AppLNo.: 51,059

Primary Examiner-Manuel A. Antonakas Attorney-Hill, Sherman, Meroni, Gross & Simpson [5 7] ABSTRACT A centralized lubrication system of the type in which a distributor periodically injects a predetermined quantity of lubri cant to each of a plurality of lubrication sites in a predetermined sequence, including sensor means associated with each of the sites, a control means which receives signals from each of the sensor means, and an auxiliary delivery means actuated by the control means to inject additional amounts of lubricant to flood the lubrication site when the sensor associated with that site indicates that an excessive temperature has been reached. The control means may also include means for resetting the sensors after the condition of excessive temperature is reached to determine whether the flooding ofthe site has been effective to reduce the temperature below the predetermined maximum. Additionally, the system may include a timer which cuts off the additional supply of lubricant and signals that the particular site is in such a condition that additional amounts of lubricant are ineffective to reduce the temperature to an acceptable value.

8 Claims, 7 Drawing Figures BACKGROUND OF THE INVENTION l. Field ofthe Invention This invention is in the field of centralized lubrication systems which operate to inject controlled amounts of lubricant periodically into a plurality of lubrication sites. The invention is particularly concerned with a control system which automatically dispenses additional amounts of lubricant to one or more sites which are overheated, and automatically terminates this additional lubricant injection if it is ineffective to reduce the temperature to below a predetermined maximum.

2. Description ofthe Prior Art Centralized lubrication systems have been previously used wherein predetermined quantities of lubricant are cyclically injected into lubrication sites. It is also fairly common to provide individual temperature sensing elements at a bearing or the like to detect excessive temperature conditions. Examples of such systems will be found in the Jones U.S. Pat. No. 2,399,036 and Reumund U.S. Pat. No. 2,961,875.

For some types of heavy machinery, it is not uncommon for a bearing to exceed a predetennined maximum permissive temperature due to short lived overload conditions. In many instances, the overheating of the bearing can be corrected if an additional amount of lubricant is promptly injected into the bearing. To accomplish this, however, requires that substantial amounts of lubricant be injected without delay. The provision of a system which will accomplish the injection of substantial quantities of lubricant into an overheated bearing automatically and which will sense the effectiveness of such injection is the principal objective ofthe present invention.

SUMMARY OF THE INVENTION The present invention is concerned with a centralized lubrication system which, for purposes of illustration, will be assumed to be a bearing lubrication system for simultaneous lubrication of a plurality of bearings. Each of the bearings being lubricated is provided with a sensor which is capable of indicating the existence of an over-temperature condition and transmitting an electrical signal in response thereto. These electrical signals are fed to a control means which utilizes the signals to operate a secondary injection system for injecting additional quantities of lubricant into the overheated bearing, flooding the bearing with additional lubricant. Timing means are also provided to reset the sensor and verify that the additional injection of lubricant has served its function of reducing the temperature to below the predetermined maximum. Additional control means are also provided which are actuated upon the expiration of the cycle of the aforementioned timer to terminate further injection of the additional lubricant into the bearing to avoid pumping copious quantities of lubricant into a bearing which is not in a condition to be benefited by the additional lubricant injection. Indicator means are also provided to notify an operator that the bearing remains overheated, so that the equipment can be shut down before catastrophic failure might occur.

BRIEF DESCRIPTION OF THE DRAWINGS Other objects, features and advantages of the invention will be readily apparent from the following description of certain preferred embodiments thereof, taken in conjunction with the accompanying drawings, although variations and modifications may be effected without departing from the spirit and scope of the novel concepts ofthe disclosure, and in which:

FIG. 1 is a somewhat schematic view of a centralized lubrication system according to the present invention for lubricating a plurality of bearings;

FIG. 2 is a view partly in elevation and partly in cross-section illustrating one type of bearing temperature sensing device which can be employed;

FIG. 3 is a somewhat enlarged sectional view of the sensing element shown in FIG. 2;

FIG. 4 is a block diagram of a control system ofthe type employed in the present invention;

FIG. 5 is a circuit diagram of one of the module units shown in the block diagram of FIG. 4;

FIG. 6 is a view of a modied form of the invention where-in the temperature sensing means is applied to the periphery of a bearing assembly; and

FIG. 7 is a cross-sectional view on an enlarged scale of the temperature sensor employed in FIG. 6.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. l, reference numeral l0 has been applied to a pump which delivers lubricant under pressure from a source (not shown) to a tee fitting 11, the pump being driven by means of a motor l2. A pressure sensitive switch 13 also communicates with the tee fitting 11 and operates to deenergize the motor 12 in the event that the discharge pressure of the pump exceeds a predetermined value.

A portion of the pump output is directed to a cyclic lubricant distributor generally indicated at reference numeral 14 of the drawings. The particular distributor is schematically illustrated in FIG. 1 and is a single line cyclic lubricant distributor of the type well known in the art. A typical illustration of such a distributor will be found in Harter U.S. Pat. No. 2,792,9I l. The details of the distributor, per se, do not form a novel part of the present invention, and any distributor system which operates to cyclically inject predetermined quantities of lubricant in sequence with a plurality of lubricating sites can be employed for purposes of the present invention.

The particular distributor 14, as shown in FIG. 1, includes an inlet block unit 15, two intennediate block units 16 and 17 and an end block unit 18. A conduit 19 is provided to direct pressurized lubricant discharged from the intermediate block unit 16 into a bearing 20, and another conduit 21 is provided to discharge the pressurized lubricant from this unit cyclically into a bearing 22. Similarly, the conduit 23 conveys the pressurized lubricant from the intermediate block unit 17 into a bearing 24 and a conduit 25 associated with the same intermediate block unit delivers pressurized lubricant to a bearing assembly 26.

Associated with each of the bearings 20, 22, 24 and 26 are sensor units 27, 28, 29 and 30, respectively. A more specic description of several types of sensor units will be made in a succeeding portion of this specification.

Inasmuch as the system operates to inject quantities of additional lubricant which flood the bearing surfaces, each of the bearing assemblies may be provided with troughs 31, 32, 33 and 34 for collecting the excess lubricant.

Another portion ofthe pressurized lubricant is conveyed via conduit 35 to serve as a secondary distribution system for injecting additional quantities of lubricant selectively into the individual bearings upon the attainment of an overtemperature condition. A branch line 36 under the control of a valve 37 operated by a solenoid 38 directs lubricant, as required, from the conduit 35 into the bearing 20. Similarly, conduits 39, 40 and 41 are provided with solenoid operated valves 42, 43 and 44 under the control of solenoids 45, 46 and 47, respectively, to deliver lubricant, as needed, to the bearings 24, 30 and 28.

The sensing elements and the various solenoids are all electrically connected to a central control box 48 which contains most of the electrical control circuitry illustrated in FIG. 4 of the drawings.

To illustrate specic embodiments of the sensor units which may be employed, reference is invited to FIGS. 2, 3, 6 and 7. FIGS. 2 and 3 illustrate one such device wherein the sensor unit is applied to a bearing housing generally indicated at reference numeral 50, the housing having a shaft 51 journaled for rotation therein. The device shown in FIGS. 2 and 3 is a combined temperature sensor and lubrication inlet, and consists of a tee fitting 52 which has one leg receiving a temperature sensing device generally indicated at reference numeral 53 and has another leg 54 used for the introduction of a lubricant into the bearing assembly. The tee tting 52 has an externally threaded leg 55 received in threaded engagement in the bearing housing 50, and has an axial bore 56 delivering the lubricant to a registering bore 57 in the bearing housing.

As best seen in FIG. 3, the temperature sensor 53 may consist of a nipple 58 havinga tapered threaded end portion 59 arranged to be received in the leg of the tee fitting 52. A hexagonal collar 60 integrally formed on the nipple 58 is provided to accommodate a wrench used in threading the nipple 58 securely within the tee fitting 52.

The actual temperature sensing of the device is accomplished through the use of a thermistor 61 having a pair of insulated leads 62 and 63 which are electrically connected to the resistance sensing circuit. The leads are secured to the leads extending from the thermistor 6l by means of a tie wrap 65. The sensorassembly is securely anchored within the hollow interior of the nipple 58 by a deposit 66 of a potting compound such as an epoxy resin.

ln the form of the invention illustrated in FIGS. 6 and 7, a bearing housing 70 is shown surrounding a shaft 71 in which it is joumaled. The temperature sensing device in this instance is illustrated at reference numeral 72 and, as best shown in FIG. 7, includes a housing 73 having a mounting hole 74 formed therein through which there is received a bolt 75 which secures the sensor assembly to the housing 70. The sensing element in the assembly is a thermistor 76 which is joined to a pair of leads 77 and 78 through a tie wrap 79 contained within a piece of shrinkable plastic tubing 80. A deposit of potting compound 81 such as an epoxy resin is used to secure the electrical sensing elements within the housing 73.

A module embodying electrical circuitry for sensing the resistance of the temperature sensitive element is illustrated in FIG. of the drawings. ln the embodiment of the invention illustrated, there are four temperature sensing units employed. The corresponding modules have been identified at reference numerals 82, 83, 84 and 85 in FIG. 4. Since the structure of the modules is identical, a description of the module 82 associated with the temperature sensor 27 will suffice for all.V

ln each module, a step-down transformer 86 has its primary winding 87 connected to a suitable source of alternating current by means of terminals 88 and 89. A secondary winding 90 applies a reduced alternating current voltage across an alternating current relay coil 91, a capacitor 92 and a parallel combination of a diode 93 and a silicon controlled rectifier 94. Half wave pulses continuously pass through the relay coil 91 in the direction permitted by the diode 93, but the relay coil 91 does not become energized by these half wave pulses.

The silicon controlled rectifier 94 is triggered from a voltage divider network including a resistor 95, the thermistor sensing element 96, a potentiometer 97, a diode 98 and a resistor 99. Typically, the resistor 95 has a resistance value of about 5,600 ohms, the potentiometer has a maximum resistance of about 180,000 ohms and the resistor 99 has a resistance of about 1,200 ohms. A reference diode such as a zener diode 100 is employed to limit the voltage applied to the gate of the silicon controlled rectifier 94.

As the resistance of the thermistor element 96 decreases due to an increase in temperature, more voltage is applied across the resistor 99 to a point where there is current flow through the gate-cathode junction of the silicon controlled rectifier 94. This action causes conduction of the silicon controlled rectifier 94 during positive half cycles applied to the anode thereof, thereby causing a full alternating current signal to be applied across the relay coil 91 to thereby energize the relay.

Energization of the relay coil 91 serves to close a pair of normally open contacts 101, to open a pair of normally closed contacts 102 and to close a pair of normally open contacts 103. The latter is in series with a nonnally closed relay contact 105 under the control of a relay coil 106. Closing of the contacts 103 insures that the thermistor element 96 is out of the circuit and applies a continuous voltage across the diode 100 and the resistor 99 suicient to maintain the silicon controlled rectier 94 conductive.

Before energization of the relay coil 91, that is, before a temperature is reached at which the silicon controlled rectifier 94 becomes conductive, an indicator light 107 is energized through the normally closed relay contact 102 from a pair of terminals 109 and 109 leading to a suitable source of alternating current voltage. Energization of the light 107 thereby indicates that the bearing temperature is below the particular temperature being sensed. When the thermistor element 96 has sensed a suiciently high temperature, however, and the silicon controlled rectifier 94 is conductive to the point of energizing the relay coil 91, a warning light 108 is then energized through the then closed contacts 101. At the same time, a voltage is developed across the lines 110 and 1 1l to serve as a control voltage initiating operation of a cycle timer 112 shown diagrammatically in FIG. 4. These energizing voltages for modules 82 through 85, respectively, are illustrated at single lines l 13 through 116, respectively, of FIG. 4.

The cycle timer 112 may be a conventional timing device including a synchronous motor which drives one or more cams to close energizing switches. The cycle timer 112 sends reset signals through lines 117, 118, 119 and 120 into the modules 82 through 85, respectively. As illustrated in FIG. 5, the reset signal is used to energize the relay coil 106 which in turn opens the normally closed relay contact 105. Opening of the relay contact 105 serves to inject the thermistor element 96 into the circuit again to resume its temperature sensing function.

When the cycle timer 112 is first energized, and control signals are passed to the modules 82 to 85, depending upon which module has sensed the excessive temperature condition, one or more control relays 121 through 124 are energized, thereby actuating their associated solenoids 38, 45, 46 or 47 to inject additional quantities of lubricant as a continuous stream into their associated bearing assemblies. Periodically, the cycle timer 112 sends its reset signal into the affected module and, if the temperature has dropped sufficiently so that it is below the predetermined maximum, the control relay 121, 122, 123 or 124, as the case may be, will be energized, and nonnal operation of the system will resume. lf, however, at the conclusion of one cycle of the timer 112 (which may involve one or more reset signals) the temperature is still excessive, the cycle timer sends a signal to line 125 to an overtime timer 126. The latter is connected by means of lines 127, 128, 129 and 130 to the respective control relays 121 through 124 to deenergize the particular relay involved. This keeps the system from pumping all of the lubricant into a particular bearing when the malfunction is such that it is incapable of being corrected by the injection of substantial amounts of lubricant. A warning device such as an indicator light 131 noties the operator that this continued malfunction exists so that the operator is then advised that the particular motor assembly has a hot bearing which cannot be corrected by flooding with additional lubricant.

The centralized control system of the present invention thus provides a substantially automatic injection system for the relief of temporary overload conditions.

I claim as my invention:

l. A centralized lubrication system for lubricating a plurality of points comprising distributor means arranged for connection to a source of pressurized lubricant and including first delivery means for delivering a predetermined quantity of lubricant to each of said plurality of points in a predetermined sequence, sensor means at each of said points of use for sensing the temperatures thereof, a thermally responsive element in each of said sensor means whose electrical resistance varies as a function of temperature, control means including said thermally responsive element as a current determining element therein, and second delivery means actuated by said control means and responsive to a change in resistance of said thermally responsive element indicative of an excessive temperature condition to deliver amounts of lubricant in excess of said predetermined quantity to the ones of said points in which the temperature is excessive until the temperature thereof is reduced.

2. The system of claim 1 which includes reset means in each of said sensor means and a cycle timing means operable upon the sensor means reaching a predetermined temperature to send a resetting signal to said reset means.

3. The system of claim 2 which includes an overtime timing means actuated at the expiration of a predetermined cycle of said cycle timing means to discontinue delivery of said additional amounts of lubricant to the ones of said points at which an excessive temperature still exists.

4. The system of claim l in which each sensor means includes a thennistor.

5. The system of claim 1 in which said distributor means is a single line cyclic lubricant distributor.

6. The system of claim 1 in which each of said sensor means includes a thermistor, a resistance sensing circuit including a relay having a coil, means for supplying said relay coil with half wave pulses, a gating device connected to said relay coil, means connecting said thermistor to said gating device whereby said relay coil is energized with half wave pulses of opposite polarity from the aforementioned pulses upon energization of the gating device by increased current flow through said thermistor, and indicator means operable by said relay upon energization of said gating device.

7. The system of claim l in which said second delivery means delivers a continuous stream of lubricant to flood the point at which the excessive temperature exists.

8. The system of claim 3 which includes a signalling means connected to said overtime timing means to indicate energization thereof.

* 1k k ik 

1. A centralized lubrication system for lubricating a plurality of points comprising distributor means arranged for connection to a source of pressurized lubricant and including first delivery means for delivering a predetermined quantity of lubricant to each of said plurality of points in a predetermined sequence, sensor means at each of said points of use for sensing the temperatures thereof, a thermally responsive element in each of said sensor means whose electrical resistance varies as a function of temperature, control means including said thermally responsive element as a current determining element therein, and second delivery means actuated by said control means and responsive to a change in resistance of said thermally responsive element indicative of an excessive temperature condition to deliver amounts of lubricant in excess of said predetermined quantity to the ones of said points in which the temperature is excessive until the temperature thereof is reduced.
 2. The system of claim 1 which includes reset means in each of said sensor means and a cycle timing means operable upon the sensor means reaching a predetermined temperature to send a resetting signal to said reset means.
 3. The system of claim 2 which includes an overtime timing means actuated at the expiration of a predetermined cycle of said cycle timing means to discontinue delivery of said additional amounts of lubricant to the ones of said points at which an excessive temperature still exists.
 4. The system of claim 1 in which each sensor means includes a thermistor.
 5. The system of claim 1 in which said distributor means is a single line cyclic lubricant distributor.
 6. The system of claim 1 in which each of said sensor means includes a thermistor, a resistance sensing circuit including a relay having a coil, means for supplying said relay coil with half wave pulses, a gating device connected to said relay coil, means connecting said thermistor to said gating device whereby said relay coil is energized with half wave pulses of opposite polarity from the aforementioned pulses upon energization of the gating device by increased current flow through said thermistor, and indicator means operable by said relay upon energization of said gating device.
 7. The system of claim 1 in which said second delivery means delivers a continuous stream of lubricant to flood the point at which the excessive temperature exists.
 8. The system of claim 3 which includes a signalling means connected to said overtime timing means to indicate energization thereof. 